Method and apparatus for introducing a weft thread into a sheet of warp threads

ABSTRACT

This invention concerns a method of introducing at least one weft thread into a sheet of warp threads so as to assist in holding the sheet together, the said method comprising employing at least one toothed wheel which is rolled transversely across the sheet periodically to raise and lower predetermined warp threads in a sequence which permits the passage of the weft thread transversely of at least a part of the sheet, and introducing the said weft thread over and under the said predetermined warp threads.

United States Patent Inventor Andrzej Wrzesien West Didsbury, EnglandAppl. No.- 792,646 Filed, Jan. 21. 1969 Patented July 27, 1971 AssigneeRolls-Royce Limited Derby, Derbyshire, England METHOD AND APPARATUS FORINTRODUCING A WEFT THREAD INTO A SHEET 0F WARP THREADS [56] ReferencesCited UNITED STATES PATENTS 773,808 11/ 1904 Pentlarge 139/28 2,769,2221 H1956 Southwell 139/291 3,039,169 6/ 1962 Frickert 139/11 3,147,7749/1964 Fontaine 139/29 3,283,788 11/1966 Bottomley 139/28 3,426,805 2/1969 Shim'well 1 39/ 123 Primary ExaminerHenry S. J audonAttorneyCushman, Darby & Cushman PATENTEUJULZ'IIHYI 3,595,276

sum 3 OF 3 Inventor Amngzar M1 in, I'ZN METHOD AND APPARATus FORINTRODUCING A WEFT THREAD INTO A SHEET or WARP TnRRAns This inventionconcerns a method and apparatus for in- 5 troducing a weft thread into asheet of warp threads so as to assist in holding the sheet together.This may, for example, be desirable if the sheet is to be passed to asubsequent treatment, such as a heat treatment. 1

According to the present invention, there is provided a method ofintroducing at least one weft thread into a sheet of warp threads so asto assist in holding the sheet together, the said method comprisingemploying at least one toothed wheel which is rolled transversely acrossthe sheet periodically to raise and lower predetermined warp threads ina sequence which permits the passage of the weft thread transversely ofat least a part of the sheet, and introducing the said weft thread overand under the said predetermined warp threads.

Preferably the weft thread is introduced during longitudinal movement ofthe sheet.

The weft thread is preferably carried by a carrier member which isreciprocated transversely of at least part of the sheet.

The sheet of warp threads may be made up of a plurality of tows of warpthreads.

Moreover both the warp and weft threads may be made up of continuousfilaments.

A plurality of weft threads, ora plurality of different por tions of thesame weft thread, may be introduced into the said sheet, the variousweft threads or said portions being longitudinally spaced apart andintroduced over and under different warp threads.

The invention also comprises an apparatus for carrying out the saidmethod comprising means for supporting a sheet of warp threads, at leastone toothed wheel for periodically raising and lowering predeterminedwarp threads of said sheet, means for rolling the toothed wheeltransversely across the sheet so that the predetermined warp threads areraised and lowered in a sequence which permits the passage of a weftthread transversely of at least a part of the sheet, and means forintroducing the said weft thread over and under the said predeterminedwarp threads.

The means for supporting the sheet may comprise means for moving thewarp threads longitudinally during the introduction of weft thread.

The means for introducing the weft thread may comprise at least onecarrier member, and means for reciprocating the or each carrier membertransversely of at least part of the sheet.

The or each carrier member is preferably a hollow needle through whichthe weft thread may pass.

Means may be provided for adjusting the width of the said sheet. Thusthe last-mentioned means may comprise a comb having teeth whosedistances apart may be varied and between which the warp threads mayextend.

Means may moreover be provided for improving the uniformity of the sheetin the transverse direction.

There may be means for detecting excess tension in the sheet and/orbreakage of a weft thread, and for stopping the machine when such excesstension or breakage is detected.

Means may be provided for heating the sheet after the weft thread orthreads has been introduced thereinto.

The invention is illustrated, merely by way of example, in theaccompanying drawings, in which:

FIGS. 1 to 3 are diagrammatic perspective views of different parts of anapparatus in accordance with the present invention.

Referring to the drawings, a creel 31 carries a number of bobbins 32each of which supports a cheese of polyacrylonitrile or other continuouscarboniferous filament.

I A tow 33 of the filaments is withdrawn from each of these cheeses andpasses through a respective nylon tube 34 and thence to a respectivenylon tube 35 in an assembly plate 36. The tubes 34, 35 serve toseparate the various tows 33 from each other to prevent the filamentsthereof from becoming en- 75 tangled and damaged, and also to limitexternal damage to these filaments.

As will be seen from FlG..1, the tows 33 which have passed through thenylon tubes35 of the'assembly plate 36 pass between teeth 37 of a comb38. The comb 38 functions as a spacing means and is constituted by alazy tongs member (not shown) which carries the said teeth 37 and whichmay be adjusted (by means not shown) so as to alter the distances of theteeth 37 from each other. Thus by adjusting the spacing of the teeth 37a variation may be made to the width and density of the sheet 40 intowhich the tows 33 are ultimately formed.

Alternatively, the width and density of the sheet 40 may be adjusted byarranging that the nylon tubes 35 can be moved towards and away fromeach other.

The tows 33 which emerge from the nylon tubes 35 and which pass throughthe comb 38 are in the form of strands of continuous filament of roughlyelliptical cross section. In order, however, to improve the uniformityof the resultant sheet 40 in the transverse direction it is necessary tospread the tows 33 out to form a homogeneous sheet having a thicknessof, say 0.005 inch. The tows 33 are therefore passed over a horizontalroller 41 and alternate tows 33 are then passed respectively above andbelow a horizontal bar 42, the upper tows passing beneath a horizontalbar 43 which is disposed adjacent to the bar 42. The tows which has thuspassed to opposite sides of the bar 42 then pass to opposite sides of astainless steel plate 44 forming part of a spreader unit 45. Laminarphosphor-bronze springs 46, which are disposed on opposite sides of theplate 44, are forced against the latter so as to effect spreading of therespective tows. The arrangement of the two sets of tows is such thatthe spaces between the tows in the bottom set coincide with thecenterlines of the tows in the top set.

All the tows then pass over a plate 50 and beneath an inflated rubbertube 51, the pressure in which is detected by a pressure switch 52 (ofknown construction) the rubber tube 51 being sandwiched between theplate 50 and a further metal plate (not shown). Thus any excess tensionin the sheet 40 (which may be caused, for example, by an entangled towon a cheese, or by a large knot which causes lodgement of the tow in oneof the nylon tubes) will cause the pressure in the rubber tube 51 torise. When the excess pressure exceeds a predetermined level, a circuit(not shown) in which the pressure switch 52 is arranged will stop thewhole apparatus.

The tension generated in the tows 33 by pulling them off their cheesesand passing them through the spreader unit is not sufficiently high andis not sufficiently uniform transversely of the sheet 40 to enable thesheet to be held together by subsequently introduced weft threads. Thesheet 40 is therefore passed between a pair of intake drafting rollers53, under a horizontal bar 54, over horizontal bars 55, 56 and between apair of outlet drafting rollers 57. The rollers 53, 57 rotate at thesame angular velocity. However, the rollers 57 are of somewhat largerdiameter than the rollers 53 and there is therefore a smallcircumferential speed differential between the rollers 53, 57 such thatthe sheet 40 will be drafted by approximately 5 percent.

This amount of draft may be modified, if desired, by making one of thepair of rollers 53 a worm roller having a square worm thread thereon.Thus by altering the width of the square worm thread thereon, it may bearranged that from to 75 percent of the filaments in the sheet 40 willbe gripped between the rollers 53, the remaining 50 to 25 percentthereof being permitted to slip progressively between the rollers 53.

The rollers 53, 57 may be driven at a speed such as to move the sheet 40continuously at a speed of about 1 to 2 yards per minute.

A bar 60 extends transversely across the sheet 40 and above the latter,and supports two carriages 61 which are slidable thereover. Each of thecarriages 61 is connected to a rod 62 of a pneumatic or hydraulic doubleacting ram 63 which may thus be used to effect reciprocation of therespective carriage 61 transversely of the sheet 40. (In order tosimplify FIG. 1, only one of the rams 63 and rods 62 is shown in itsentirety).

Instead of providing rams 63 other prime movers such as lever and camsystems and linear induction motors may be used.

Each of the carriages 61 supports a freely rotatable toothed wheel 64and a hollow needle 65, which extends to a position adjacent the bottomof the toothed wheel 64. The needles 65 may be made of stainless steelthick wall tubing and may be gradually tapered along their lengths. Theteeth of the toothed wheels 64 are formed by providing a plurality ofangularly spaced-apart slots 66 which extend to the periphery of thewheel and throughout the axial length thereof. The width of each ofthese slots is such as to permit the entry thereinto of a portion of atow.

The slots 66 in the toothed wheels 64 may be relatively narrow comparedwith the width of the unslotted parts around the circumference of thetoothed wheels 64 which alternate with between them.

A weft thread 70 is introduced through each of the needles 65 so as toemerge adjacent to the bottom of the respective toothed wheel 64.

Thus as each carriage 61 is reciprocated across the respective part ofthe sheet 40, the wheel 64 engages the warp threads of the sheet 40 soas to be rotated thereby and serves periodically to lower predeterminedwarp threads in a sequence which permits the passage of the weft thread70 so that the latter passes over the said predetermined warp threadsand under all remaining warp threads.

As will be seen from FIG. 1, the arrangement is such that each of thetoothed wheels 64 is moved between a position in which it is disposedbeyond the sheet 40 to a position in which it has moved past thecenterline of the sheet. Thus, when the parts are in the position shownin FIG. 1, the portion of the weft thread 70 which has been introducedby the right-hand needle 65 will be trapped between the varioustensioned warp threads of the sheet and, due to the longitudinalmovement of the latter, will have been carried away from the respectivetoothed wheel 64. At the same time, the left-hand needle 65 will havebeen introduced to its maximum extent into the sheet 40 and, as it iswithdrawn, it will leave the weft thread behind it embedded in the sheet40. Thus in the construction shown in the drawings, two weft threads areemployed, each of which extends from its respective side of the sheet 40to a position beyond the longitudinal centerline of the sheet. Therethus may be an overlap of, say 3 inches between these two weft threadsat the center of the sheet 40.

When spun yarn is used for the weft thread 70, it is not necessary tohave any mechanism to retain the weft thread 70 in the sheet. However,for continuous filament yarn, a hook system (not shown) can be used toprevent the weft thread from being pulled out of the sheet during thewithdrawal of the needles.

Since the wheels 64 will be frictionally rotated by engagement with thesheet 40, they will continue to rotate even when moved to a positionfree of the latter. Indeed, means may be provided deliberately to rotatethem. As a consequence, the angular positions of the slots 66 in a wheel64, will, with respect to the sheet 40, vary every time the respectivecarriage 61 is reciprocated. As a consequence, and as shown in FIG. 1,different portions 71, 72 of the same weft thread 70 which arelongitudinally spaced apart will be introduced over and under differentwarp threads so as to produce a substantially random weave.

To prevent unnecessary rubbing, means (not shown) may be provided so asto lift each of the wheels 64 out of contact with the sheet 40 wheneverthe respective needle 65 is withdrawn therefrom. Thus a pneumatic rammay be used for this purpose.

Each of the weft threads 70 is withdrawn from a cheese 73 and, on itsway to its respective needle 65, passes a weft break detector 74. Thedetectors 74 may be photoelectric, capacitive, electromechanical, orincorporating fluid logic devices, and are such that in the event ofweft breakage, a signal is provided which stops the apparatus.

After the sheet 40, which has had the weft threads 70 so introduced, haspassed between the rollers 57, it passes between two plates 75 of aheating unit 76. The heating unit 76 and means for moving it may be ofknown constructions, as shown for example in US. Pat. No. 2,769,222.Each of the plates 75 may, for example, be constituted by a steel platecoated with polytetrafluorethylene. Each of the plates 75 carries aninfrared heater 77, the temperature of which is maintained reasonablyconstant by a thermostat (not shown). The sheet 40 is thus heated whileunder tension so that its material will stretch, and protrudingfilaments will be shrunk, and its modulus of elasticity will beincreased. Thus a sheet of material will be produced which is morehighly orientated so as to facilitate its consequent handling.

Whenever the machine stops, the plates 75 and their heaters 77 are movedaway from the sheet 40 (by means not shown), but the heaters 77 are notswitched off.

If desired, high frequency dielectric heating can be used instead.

In order to produce a stable beam of the sheet 40 which has been soheated, it is necessary to introduce at intervals, narrow strips ofpaper 78 called collars at the edges of the beams. This operation isusually performed by hand. Semiautomatic means are illustrated at 80(FIG. 3) to allow quicker and easier insertion of the collars 78. Thesystem can, if desired, be fully automated to deal either with thecontinuous length of collar 78 or to cut and insert short lengths asrequired.

The sheet 40 is thus wound onto a spool 81 which is rotated by means ofan electric motor 82 by way of a reduction gear 83 and hydraulicdashpots 84. The surface velocity of the spool 81 is considerably higherthan the velocity of the sheet 40 which has just been heat treated, andtension is thus generated in the latter due to slip in the hydraulicdashpots 84 that act as couplings. The tension in the sheet can beadjusted by changing the torque settings of the hydraulic dashpots 84 orby changing the speed ratio between the sheet 40 and the circumferentialvelocity of the spool 81.

Torque electric motors can be used instead of hydraulic dashpots. Inthis case, torque values are changed by altering the voltages suppliedin the motors.

In either case, a condition of constant tension can be achieved and thelevel of tension can be preset. The spools 81 may be wound to a diameterof 24 inches, but larger diameters can also be used ifdesired.

As will be appreciated, although the invention has been discussed abovein relation to the production of a sheet of polyacrylonitrile tows, theinvention may also be used to provide fabrics of novel constructionfrom, say, natural fibers.

Iclaim:

1. A method of introducing at least one weft thread into a sheet of warpthreads so as to assist in holding the sheet together, said methodcomprising moving the sheet of warp threads longitudinally in asubstantially flat plane, employing at least one freely rotatabletoothed wheel which is reciprocated transversely across the sheet and inengagement with the warp threads to effect rotation of the toothed wheelto periodically depress predetermined warp threads out of said flatplane, while leaving remaining warp threads in said flat plane, in asequence which permits the passage of the weft thread transversely of atleast a part of the sheet, and introducing the said weft thread betweensaid predetermined warp threads and said remaining warp threads, andmoving the toothed wheel so that, at the end of each completereciprocation thereof, the toothed wheel is disposed beyond the sheetand out of engagement with the warp threads.

2. A method as claimed in claim 1 in which two weft threads and twotoothed wheels are employed, each weft thread and toothed wheel beingcarried by a carriage which is reciprocated transversely of a part onlyof the sheet, the carriages being moved to opposite sides of the sheet.

3. A method as claimed in claim 1 in which the sheet of warp threads ismade up of a plurality of tows of warp threads.

4. A method as claimed in claim 1 in which the warp and weft threads aremade up of continuous filaments.

5. Apparatus for introducing at least one weft thread into a sheet ofwarp threads so as to assist in holding the sheet together, saidapparatus comprising means for moving a sheet of warp threadslongitudinally, at least one freely rotatable toothed wheel engageablewith the warp threads for periodically depressing predetermined warpthreads of said sheet, means for reciprocating the toothed wheeltransversely across the sheet and in engagement with the warp threads toeffect rotation of the toothed wheel so that the predetermined warpthreads are lowered in a sequence which permits the passage of a weftthread transversely of at least a part of the sheet, and means forintroducing the said weft thread over the said predetermined warpthreads and under the remaining warp threads, the toothed wheel, at theend of each complete reciprocation thereof, being disposed beyond thesheet, and out of engagement with the warp threads.

6. Apparatus as claimed in claim 5 in which two weft threads and twotoothed wheels are employed, the means for introducing each weft threadcomprising a carriage which carries both a carrier member for the weftthread and a toothed wheel, and means for reciprocating each carriagetransversely of a part only of the sheet, said carriages beingpositioned for movement to opposite sides of the sheet.

7. Apparatus as claimed in claim 6 in which the carrier member is ahollow needle through which the weft thread may pass.

8. Apparatus as claimed in claim 5 in which means are provided forimproving the uniformity of the sheet in the transverse direction.

9. Apparatus as claimed in claim 5 in which there are means fordetecting excess tension in the sheet and for stopping the apparatuswhen such excess tension is detected.

10. Apparatus as claimed in claim 5 in which there are means fordetecting breakage of a weft thread, and for stopping the apparatus whensuch breakage is detected.

11. Apparatus as claimed in claim 5 in which means are provided forheating the sheetafter the weft thread has been introduced thereinto.

1. A method of introducing at least one weft thread into a sheet of warpthreads so as to assist in holding the sheet together, said methodcomprising moving the sheet of warp threads longitudinally in asubstantially flat plane, employing at least one freely rotatabletoothed wheel which is reciprocated transversely across the sheet and inengagement with the warp threads to effect rotation of the toothed wheelto periodically depress predetermined warp threads out of said flatplane, while leaving remaining warp threads in said flat plane, in asequence which permits the passage of the weft thread transversely of atleast a part of the sheet, and introducing the said weft thread betweensaid predetermined warp threads and said remaining warp threads, andmoving the toothed wheel so that, at the end of each completereciprocation thereof, the toothed wheel is disposed beyond the sheetand out of engagement with the warp threads.
 2. A method as claimed inclaim 1 in which two weft threads and two toothed wheels are employed,each weft thread and toothed wheel being carried by a carriage which isreciprocated transversely of a part only of the sheet, the carriagesbeing moved to opposite sides of the sheet.
 3. A method as claimed inclaim 1 in which the sheet of warp threads is made up of a plurality oftows of warp threads.
 4. A method as claimed in claim 1 in which thewarp and weft threads are made up of continuous filaments.
 5. Apparatusfor introducing at least one weft thread into a sheet of warp threads soas to assist in holding the sheet together, said apparatus comprisingmeans for moving a sheet of warp threads longitudinally, at least onefreely rotatable toothed wheel engageable with the warp threads forperiodically depressing predetermined warp threads of said sheet, meansfor reciprocating the toothed wheel transversely across the sheet and inengagement with the warp threads to effect rotation of the toothed wheelso that the predetermined warp threads are lowered in a sequence whichpermits the passage of a weft thread transversely of at least a part ofthe sheet, and means for introducing the said weft thread over the saidpredetermined warp threads and under the remaining warp threads, thetoothed wheel, at the end of each complete reciprocation thereof, beingdisposed beyond the sheet, and out of engagement with the warp threads.6. Apparatus as claimed in claim 5 in which two weft threads and twotoothed wheels are employed, the means for introducing each weft threadcomprising a carriage which carries both a carrier member for the weftthread and a toothed wheel, and means for reciprocating each carriagetransversely of a part only of the sheet, said carriages beingpositioned for movement to opposite sides of the sheet.
 7. Apparatus asclaimed in claim 6 in which the carrier member is a hollow needlethrough which the weft thread may pass.
 8. Apparatus as claimed in claim5 in which means are provided for improving the uniformity of the sheetin the transverse direction.
 9. Apparatus as claimed in claim 5 in whichthere are means for detecting excess tension in the sheet and forstopping the apparatus when such excess tension is detected. 10.Apparatus as claimed in claim 5 in which there are means for detectingbreakage of a weft thread, and for stopping the apparatus when suchbreakage is detected.
 11. Apparatus as claimed in claim 5 in which meansare provided for heating the sheet after the weft thread has beenintroduced thereinto.